Reason

The refractory lining in a Claus Thermal Reactor has different expansion/contraction coefficients from the reactor’s steel shell, which supports the Delta Controls Model HTP Thermocouple. As the reactor is brought up to operating temperature, the refractory shifts relative to the vessel shell, to which the HTP is rigidly connected. The potential damage to the HTP element caused by movement of the refractory relative to the vessel shell (primarily the "shear" axis movement) is minimized by mounting the nozzle/HTP on the top centerline area of the reactor.

During the expansion, contraction, and aging of refractory materials, bits and pieces become dislodged. In a vertical installation, these "bits and pieces" tend to fall harmlessly down and into the vessel. However, in a horizontal installation, they fall on the Refractory Well, accumulating around the lower side of it. This creates pressure points, where subsequent expansion/contraction cycles could fracture the well.

2

Reason

Installation of the HTP in a Claus Thermal Reactor requires the use of the HRW Refractory Well that fits into and rests on the vessel refractory. The small Refractory Well utilizes a 1.75-inch O.D. collar to support it from the bottom of the recessed hole in the refractory and to hold it in the proper position. A 1.94" (50mm) minimum size nozzle I.D. affords enough space to install the proper amount and kind of insulation necessary to protect the nozzle and shell from excessive heating.

The small size refractory well collar must not come into contact with the I.D. of the nozzle as the refractory liner moves relative to it. Such an occurrence will fracture the refractory well. This requirement is met by providing a recess large enough for the refractory well collar to drop into and be below the inside surface of the vessel shell. The collar does not contact the nozzle/shell during movement, and adequate room for insulation to protect the nozzle is provided.

3

No refractory should be installed inside the nozzle. No refractory (or mortar) should protrude up into the nozzle above the top surface of the refractory liner.

Reason

Refractory in the nozzle defeats a major advantage of the Delta HTP. The combination of the Refractory Well, Woven Mineral Discs and Pressed Mineral Discs are key to realization of the long life expectancy and good value of the HTP. If refractory material protrudes up into the nozzle above the bottom of the vessel shell, there is not adequate clearance for the Refractory Protective Well and the nozzle insulation to do their job.

If, through movement of the refractory, the Element Well contacts the Refractory Well, it is probable that one or both wells will be broken. This will cause subsequent failure of the thermocouple element due to corrosion from the reaction gases.

Lining the nozzle wall with castable also creates a smaller I.D. in the nozzle and limits the effectiveness of the insulation pieces that allow movement of the refractory without damaging the ceramic components of the HTP. The Delta Model HNP insulation components have proven to provide adequate insulating properties while minimizing space for sulphur to precipitate into a solid. Solid sulphur acts like castable and can also cause mechanical damage to the HTP components.

4

Proper installation requires that a 1.62 to 1.67 inch (41 to 42mm) hole must be created through the refractory. The hole must be centered in the nozzle, and must be perpendicular to the nozzle flange face. A 1.87 to 2.00 inch (47 to 50mm) by 1.0 (25mm) deep recess must also be created in the refractory on the centerline of the nozzle.

The Delta Controls Model HRM Installation Mandrel provides the most effective and accurate means to create the proper cavity and hole for installation of the HTP. To insure the proper clearances between the Element Well and the Refractory Well, it is necessary that the components be installed on the nozzle centerline, at the design elevation, and perpendicular to the face of the mounting flange. The Mandrel is equipped with a "Stop-Disc" that prevents refractory material from entering the base of the nozzle and upsetting the clearance between the bottom of the Element Well and the inside bottom of the Refractory Well. The "Stop-Disc" also creates a concentric recessed hole for the collar of the Refractory Well to rest against. It also prevents any pressure point loading on the collar/tube.

5

Reason

Drilling long distances into a nozzle often creates an "off-center" bore and possibly misalignment relative to the flange face. This occurs because it is difficult to establish accurate alignment when mounting the drill assembly and starting the core drill. Taller nozzles intensify the difficulty and lower the probability of obtaining a proper result.

If the HTP Thermocouple is to be installed through existing refractory, then drilling is probably the only means available to create the required bore hole. In this case, be deliberate and very careful; put the hole on the exact centerline of the nozzle and drill at 90° to the face of the mounting flange.

If it has been determined that drilling is to be used on a new refractory job, Delta still recommends that the Mandrel be used, except that the Mandrel is to be cut off slightly, 0.75" (19mm), below the inner surface of the vessel shell. This permits the use of the "Stop-Disc" that keeps refractory from entering the base of the nozzle and at the same time, permits installation of refractory brick or castable without having to work around the mandrel tube. The Mandrel tube protrusion leaves a shallow hole in the refractory which acts as an effective guide for starting the core drill. This minimizes the possibility of misalignment or "off-center" drilling. Off center or misaligned bores, once created, cannot easily be corrected.

NOTE: The drilled hole must be at 90° to the face of the mounting flange on the vessel. If the drill is set up using a level; be sure that the reference is the flange face and not the earth’s gravity.

6

To determine if the refractory work is suitable for the proper installation of the HTP. Check the dimensions to be sure that they are correct, that there will be no interference between components, and that spacing is correct. This will help ensure that no failures occur due to movement of the refractory, or from interference between components.

Reason

If the refractory work results in improper dimensions or misalignment of the bore, the HTP components may fail as the vessel is brought on line and movement of the refractory begins.

Steps to check that the installation was properly performed:

1. Check the through/recess hole sizes and other dimensions for accuracy.
2. Assure that the bottom surface of the recess hole is smooth, flat and 1.0 inch (25mm) deep. If it is uneven, the "bumps" must be removed. The top of the well collar must be below the bottom surface of the vessel shell. (This is why the use of the Installation Mandrel with the "Stop-Disc" is important).
3. If drilling work was performed…

1. Place a bright light in the vessel directly below the thru-bore and observe that the thru-bore is clean with no protrusions. Also, using the light, observe the alignment of the bore relative to the centerline of the vessel nozzle. All diameters should appear concentric to each other.
2. Check that the thru-bore and recess hole diameters are correct.